microbio quiz 1/test 1 pt 2

trematodes: general characteristics

• phylum Platyhelminthes; class Trematoda (aka flukes)

• adults = dorsoventrally flattened + may infect intestine, liver, lungs, lymphatics, or blood vessels

• most = hermaphroditic (have both male + female reproductive organs)

  • EXCEPT BLOOD FLUKES

• eggs are usually operculated

  • EXCEPT BLOOD FLUKES

• most require a SNAIL as the first intermediate host; many require a second host (e.g. fish or crab)

miracidium

• larval stage that hatches from eggs in water and infects SNAIL

cercaria

• larval stage that leaves the snail

• in schistosomes, this is infective to humans by skin penetration

• PENETRATION

metacercaria

• encysted larval stage on vegetation or in fish/crab

• this is INFECTIVE for most non-blood flukes

• INGESTION

adult

• lives in target organ/site and produces eggs

• adult site helps predict specimen source

intestinal flukes

• organisms

  • Fasciolopsis buski

  • Metagonimus yokogawai

  • Heterophyes heterophyes

• classic exposure

  • water plants or raw/undercooked fish

• likely specimen

  • stool

liver flukes

• organisms

  • Fasciola hepatica

  • Clonorchis sinensis

• classic exposure

  • watercress/vegetation

  • raw/pickled fish

• likely specimen

  • stool and/or bile

lung fluke

• organisms

  • Paragonimus westermani

• classic exposure

  • raw/undercooked crab or crayfish

• likely specimen

  • SPUTUM

  • stool

blood flukes

• organisms

  • Schistosoma mansoni

  • S. haematobium

  • S. japonicum

• classic exposure

  • freshwater skin exposure

• likely specimen

  • stool

  • urine

look alikes

• F. buski and F. hepatica EGGS

• Metagonimus/Heterophyes/Clonorchis EGGS

Faciolopsis buski is also known as?

• GIANT intestinal fluke

F. buski - region

• Far east regions

  • china

  • vietnam

  • india

F. buski - reservoir hosts

• dogs

• pigs

F. buski - transmission stage and source

• ingestion of metacercariae on raw or undercooked water plants

F. buski - life cycle

1. eggs reach water and mature

2. SNAIL is required 1st intermediate host

3. METACERCARIAE encyst on aquatic vegetation

4. humans ingest contaminated water plants

5. adults mature in the intestine and EGGS pass in STOOL

F. buski - infective vs diagnostic stages

• infective = metacercariae on water plants

• diagnostic = eggs in stool

F. buski - clinical infection + diagnosis

• often asymptomatic (light worm burden)

• heavy infections:

  • mechanical + toxic damage of small intestine

  • persistent diarrhea, anorexia, edema, ascites, intestinal obstruction, eosinophilia

• pt diagnosis

  • travel history, food history, symptoms, lab findings

F. buski - laboratory finding + sample type

• adult or egg

• EGG IN FECES is more common

• CANNOT BE DIFFERENTIATED FROM FASCIOLA HEPATICA EGGS

  • if only egg: report as “F. buski/ F. hepatica”

F. buski - egg

• yellow-brown

• elliptical

• approximately 130-140 × 80-85 microns

• small operculum (small lid that can open/close) may not always be visible

• important!!!!

  • CANNOT BE DIFFERENTIATED FROM FASCIOLA HEPATICA EGGS

  • if only egg: report as “F. buski/ F. hepatica”

F. buski - adult

• flattened fluke

• approx. 2-7 cm

metagonimus/heterophyes - region

• Far east

• middle east

Metagonimus yokogawi and Heterophyes heterophyes

metagonimus/heterophyes - transmission stage + source

• ingestion of metacercariae in raw/undercooked fish

metagonimus/heterophyes - clinical infection + diagnosis

• often asymptomatic

• heavy burden:

  • diarrhea

  • colic

  • LOOSE STOOLS W MUCUS

metagonimus/heterophyes - lab diagnosis

• eggs = diagnostic and found in stool

• 
  

metagonimus/heterophyes - eggs

• approx. 28-30 microns long

• may have vase or flask shape

• embryonated and operculated

• inconspicuous shoulders

• important!!!!!

  • EGGS RESEMBLE ONE ANOTHER + CLORONCHIS SINENSIS

metagonimus/heterophyes - adult

intestinal flukes comparison chart

Fasciola hepatica is also known as?

• sheep liver fluke

  • infection in sheep is called liver rot

F. hepatica - region

• found in cattle & sheep raising areas

  • parts of southwestern United States

F. hepatica - transmission stage + source

• ingestion of metacercariae on raw water vegetation

  • esp watercress

F. hepatica - life cycle

1. eggs pass in feces and MUST reach WATER

2. SNAIL is required as FIRST intermediate host

3. cercariae leave snail and encyst as metacercariae on aquiatic vegetation

4. humans ingest metacercariae → larvae migrate to the liver and biliary tract

F. hepatica - infective vs diagnostic

• infective = metacercariae on aquatic vegetation

• diagnostic = egg in feces and/or bile

F. hepatica - clinical infection + diagnosis

• tissue damage may occur during metacercarial migration thru liver tissue

• adults may obstruct the biliary ducts or gallbladder

• symptoms: OBSTRUCTIVE JAUNDICE, vomiting, fever, ENLARGED LIVER, CIRRHOSIS, diarrhea, eosinophilia, inflammation, and secondary bacterial infection

F. hepatica - lab diagnosis

• recovery of eggs in feces and/or bile fluid

• adult recovery is possible

F. hepatica - egg

• yellow-brown

• small operculum

• approx. 130-150 × 60-90 microns

• important!!!!

  • EGGS INDISTINGUISHABLE FROM F. BUSKI

  • report as “F. buski/F. hepatica egg”

F. hepatica - adult

• approx 3 cm long

• conical anterior projection

• broadly pointed posterior end

Clonorchis sinensis is also known as ?

• chinese liver fluke

C. sinensis - region

• mainly far east

  • china, japan, korea, vietnam

C. sinensis - reservoir hosts

• dogs

• cats

C. sinensis - transmission stage and source

• ingestion of metacercariae in raw, undercooked, or pickled FISH

• adults live in bile ducts

C. sinensis - life cycle

1. eggs pass in feces and reach water

2. SNAIL is the first intermediate host

3. FISH serve as the second intermediate host

4. humans ingest METACERCARIAE in raw, undercooked, or pickled FISH

5. adults live in the bile ducts and eggs may be found in feces or biliary contents

C. sinensis - clinical infection + diagnosis

• light infections = few/no symptoms

• heavy infections = inflammation, diarrhea, pain, fibrosis, obstruction of bile duct

• complications = obstructive jaundice, cirrhosis, neoplasm of bile ducts

C. sinensis - lab diagnosis

• recovery of eggs in feces and/or biliary contents

C. sinensis - egg

• eggs are diagnostic

• broad, ovoid egg w thick brown shell

• approx. 29-35 microns long

• operculum has clearly demarcated shoulders

• KNOB at the opposite end, may show COMMA SHAPED POSTERIOR APPENDAGE

C. sinensis - adult

• adults may be recovered from bile duct aspiration

• adults are approx 1-2.5 cm

liver flukes comparison chart

Pragonimus westermani is also known as ?

• the oriental lung fluke

P. westermani - region

• primarily in southeast asia, latin america, africa

P. westermani - transmission stage + source

• ingestion of raw or undercooked crabs or crayfish (shellfish) containing metacercariae

  • metacercariae excyst in the small intestine, then burrows into the diaphragm into the lungs

  • adults live within capsules in the bronchioles

P. westermani - life cycle

1. eggs leave the body in sputum or feces

2. larvae develop through SNAIL and CRUSTACEAN hosts

3. humans ingest METACERCARIAE in raw/undercooked CRAB or CRAYFISH

4. adults mature in the lungs

P. westermani - clinical infection + diagnosis

• light infections = asymptomatic

• heavy infections = persistent cough, chest pain, and hemoptysis

• lung inflammation = infiltration of eosinophils and neutrophils and fibrotic capsule formation around the worm

P. westermani - lab diagnosis

• recovery of eggs in sputum and/or feces

• SPUTUM IS BLOOD TINGED W RUSTY BROWN FLECKS

• complement fixation test may also help w extrapulmonary infections

P. westermani - egg

• eggs are diagnostic (sputum = primary diagnostic specimen)

• ovoid egg

• approx. 80-118 × 48-60 microns

• operculum has VERY SMALL SHOULDER + THICKENED SHELL AT OPPOSITE END

• may also be found in feces if swallowed

P. westermani - adult

• live within capsules in bronchioles

schistosoma spp - how they differ

• male and female adult worms are SEPARATE forms

• female lives INSIDE THE MALE within the gynecophoral canal

• eggs are UNOPERCULATED

• adults are CYLINDRICAL rather than dorsoventrally flattened

• humans infected when CERCARIAE PENETRATE SKIN in contaminated freshwater

S. mansoni

• geography: Africa, South America, West Indes, Puerto Rico

• adults found in: venules of LARGE INTESTINE

• egg specimen: FECES

S. japonicum

• geography: far east

• adults found in: venules of SMALL INTESTINE

• egg specimen: FECES

S. haematobium

• geography: east africa and middle east

• adults found in: veins surrounding BLADDER

• egg specimen: URINE

Schistosomiasis: clinical infection

• skin entry

  • swimmer’s itch: dermatitis from cercariae w small papules, edema, erythema, intense itching

• larval migration

  • urticaria, fever, malaise

• egg production/migration

  • major acute damage occurs as eggs move through tissues

Schistosoma - egg production/migration leads to:

• S. mansoni: stool w blood and mucus

• S. japonicum: stool w blood and mucus; KAYETAMA FEVER

• S. haematobium: hematuria and dysuria

Schistosoma - chronic infections

• granuloma formulation, venous scarring, ascites, pain, anemia, hypertension, hepatomegaly, splenomegaly

• S. haematobium chronic complications: urine retention, UTIs

Schistosoma - lab diagnosis

• S. mansoni/japonicum: eggs in feces

• S. haematobium: eggs in urine

Schistosoma eggs

• oval w species specific spine location

• NO SHOULDERS , NO LIDS

• peak excretion time for eggs is 12 PM - 2 PM

S. mansoni

• lateral spine

• feces specimen

S. haematobium

• terminal spine

• urine specimen

S. japonicum

• small curved rudimentary spine

• feces specimen

Foodborne flukes vs Blood flukes chart

large operculated eggs consider:

• Fasciola/Fasciolopsis or Paragonimus depending on specimen and type

small operculated eggs compare:

• Clonorchis, Metagonimus, and Heterophyes

stage and specimen review chart

cestode anatomy vocab

• strobila = adult body

• scolex = “head” attachment organ

• rostellum = tip of scolex; may be armed with hooks

• proglottids = body segments added during growth

• gravid proglottid = fertilized egg within proglottid

• eggs contain an oncosphere = embryo w 3 pairs of hooks

Diphyllobothrium latum - transmission stage + source

• pleroceroid larvae in pickled/raw/undercooked freshwater fish

• adults live in the jejunum ; usually just 1 worm

D.latum - life cycle

1. eggs passed in feces reach water

2. coracidium is ingested by cyclops/copepod

3. fish ingests copepod; pleroceroid develops in fish tissue

4. humans ingest raw or undercooked freshwater fish

5. adult matures in intestine ; eggs are passed in stool

D. latum - infective vs diagnostic stage

• diagnostic: egg in stool

• infective: pleroceroid larva

D. latum - clinical infection + diagnosis

• usually asymptomatic

• vague GI symptoms - nausea, vomiting, etc

• VITAMIN B12 DEFICIENCY + MEGALOBLASTIC ANEMIA

lab finding + sample type

• egg in stool

• can also find scolex and proglottid

• diagnostic structures: scolex, egg, proglottid

D. latum - egg

• yellow - brown

• distinct OPERCULUM

  • NO SHOULDERS

• small KNOB at the opposite end

• UNEMBRYONATED when passed

D. latum - scolex + proglottids

• scolex:

  • 2 sucking grooves

  • elongated spoon shaped

• proglottids:

  • wider rather than long

  • CENTRAL rosette shaped uterus

Taenia saginata - transmission stage + source

• BEEF tapeworm

• ingestion of raw/undercooked meat containing cysticerus larvae

• adults attach to mucosa of small intestine

Taenia solium - transmission stage + source

• PORK tapeworm

• ingestion of raw/undercooked meat containing cysticerus larvae

• or EGGS → cysticercosis

• adults attach to the small intestinal mucosa

Taenia spp - taeniasis symptoms + lab findings

• human ingests CYSTICERUS LARVA in beef or pork

• adult worms develop in small intestine

• eggs/proglottids may be seen in stool

• pig/cow = intermediate host

• BOTH T. sginata and T. solium

Taenia spp - cysticercosis symptoms + lab findings

• human ingests infective eggs of T. solium

• human becomes accidental intermediate host

• eggs = NOT diagnostic focus ; TISSUE LARVAE require imaging/biopsy/serology

• larvae dodge in TISSUES (muscle, eye, brain)

Taenia spp - egg

• diagnostic but DO NOT SPECIATE

• spherical

• walnut - brown

• smooth thick shell w RADIAL STRIATIONS

• 6-hooked oncosphere may not be visible

Tenia spp - scolex

• allows speciation

  • T. saginata

    • NO HOOKS

    • < 5mm

  • T. solium

    • 4 SUCKERS

    • double row of 25-30 HOOKLETS

      • evil one causes worse infection (cysticercosis) - has sharp teeth (hooks)

Taenia spp - proglottids

• allow speciation

  • T. saginata

    • 15-20 uterine branches

    • cow = bigger = MORE branches

  • T. solium

    • 7-13 uterine branches

    • pig = smaller = LESS branches

Taeniasis treatment + prevention

• SCOLEX EXPULSION = essential

  • worm will regrow otherwise

• adequately cook meat

• freeze meat below 10 C

Hymenolepis spp - transmission stage + source

• H. nana = dwarf tapeworm

  • eggs ingested by humans in contaminated soil/ f/o route - autoinfective common in children

  • NO INT. HOST REQUIRED

• H. diminuta = RAT tapeworm

  • eggs/arthropod-flea ingested by human in contaminated soil/ f/o route

  • FLEA = intermediate host

Hymenolepis spp. life cycle

1. eggs ingested by humans in contaminated soil or f/o route

2. H. nana can complete cycle WITHOUT intermediate host

3. AUTOINFECTION can maintain/increase worm burden

4. H. diminuta typically involves ingestion of an infected arthropod/ flea

Hymenolepis spp - clinical infection + diagnosis

• light infection = asymptomatic

• MANY worms = headache, irritability, dizziness, GI symptoms

Hymenolepis spp - lab diagnosis

• EGG identification in feces

• adults + proglottids = RARELY SEEN IN STOOL

H. nana vs H. diminuta egg

• H. nana

  • gray color

  • hollow lemon oncosphere

  • 4-8 POLAR FILAMENTS outside oncosphere

• H. diminuta

  • gray/straw colored

  • hollow lemon oncosphere

  • NO POLAR FILAMENTS

H. nana - adult + scolex

• 40 mm long

• small colex w 4 SUCKERS

• ROSTELLUM W SPINES

  • egg ID = still most common lab approach

Diplylidum caninum - transmission stage + source

• tapeworm of DOGS and CATS

• ingestion of FLEAS containing the LARVAL CYSTICERCOID stage

• human = accidental hosts

  • mainly children due to close pet exposure

D. caninum - life cycle

1. egg packets/ proglottids pass from infected dog or cat

2. flea larvae ingests eggs

3. cysticercoid larva develops in flea

4. dog/cat or human ingests infected flea

5. adult tapeworm develops in intestine

D. caninum - infective vs diagnostic stages

• infective: cysticercoid larva inside flea

• diagnostic: proglottids (eggs)

D. caninum - clinical infection + diagnosis

• pets: behavior relieve anal itching “butt scooting”

• humans = usually asymptomatic + mild GI symptoms

• SPARGANOSIS

  • most common in SE asia

  • often seen in the eye

    • internal abscesses, cysts, subq nodules

  • associated w: ingestion of procercoid in copepod (water)/ plerocercoid larvae in other animals

D. caninum - lab diagnosis

• macroscopic (with eyes) ID of PROGLOTTIDS IN STOOL

  • may be motile when freshly passed

• microscopic ID of EGGS in STOOL

  • large packets containing 15-25 eggs

D. caninum - proglottids and scolex

• proglottids

  • 2 GENITAL PORES

  • resemble PUMPKIN SEEDS

• scolex

  • 4 suckers

  • ARMED ROSTELLUM

Echinococcus granulosus - transmission stage + source

• HYDATID = just E. granulosus → HYDATID tapeworm

• INGESTION of EGGS containing HEXACANTH EMBRYO from food/water/fomites contaminated w DOG FECES

E. granulosus - hosts

• human = accidental hosts

• DOG = definitve host

• SHEEP/ other herbivores = intermediate host

• found worldwide, common in SHEEP raising areas